Black powder composition



Patented Feb. 11, 1936 PATENT OFFICE BLACK POWDER COMPOSITION ClarenceW. Brooks, Jr., Woodbury, N. J assignor to E. I. du Pont de Nemours &'Company, Wilmington, Del., a corporation of Delaware No Drawing.Application May 18, 1933,

Serial No. 671,700

12 Claims. (01. 52-17) g This invention relates to modified black powdercompositions, and more particularly to such compositions containingammonium nitrate as a portion of the oxidizing material.

' The composition of black powder generally has consisted essentially ofpotassium or sodium ni-' trate, sulfur, and charcoal. In the blackblasting powders in common use in this country, sodium nitrate has beenthe oxidizing ingredient used, and a representative composition prior tothe present invention has comprised approximately 72% sodium nitrate,10% sulfur, and 18% charcoal.

The advantages of black blastingpowder as a l3 commercial explosive havebeen that it possesses a relatively low velocity'of decomposition, indistinction from the high velocity dynamites. Because of this lowvelocity, in the blasting down of coal for example, a larger percentageof lump coal 20 is obtained by the use of black powder. Black blastingpowder has been used in the granular form until recent years, the grainsbeing given a smooth polished surface coating by the operation known asglazing.

. used powder at the present time, however, is in the form ofcylindrical pellets wrapped in paper sticks similar to dynamitecartridges. Black blasting powder pellets are ordinarily'made in blocksabout 2" in length and of any desired di- 30 ameter, up to approximately2", for example.

While sodium nitrate has been the customary oxidizing ingredient in suchpowders, various proposals have been made to replace a portion of the,sodium nitrate by ammonium nitrate. Such a' replacement has had' anumber of advantages, particularly in giving greater potential strengthto the powders, since ammonium nitrate produces gaseous products only oncombustion, whereas a relatively large proportion of the sodium nitrateis left as solid residue. A further advantage comes from the fact thatthe use of ammonium nitrate as a partial replacement of the sodiumnitrate allows the attainment of a lower density pellet powder. This lowdensity feature is desirable in many cases, since it gives a greaternumber of sticks per pound of explosive, the strength per 1 stick stillbeing sufiicient to give the desired execution. g

Ammonium nitrate is a highly hygroscopic 50 compound and it is necessaryin the case of pellets containing it, and in fact with all pellets, tofree the pellets from moisture before final packing, by drying at arelatively elevated temperature, for example 95 C. In drying ammoniumnitrate 5 powders, the disadvantage has been encountered The mostcommonlythat these powders exhibit a tendency to spontaneousignition ondrying at elevated tempera-'- tures, thereby introducing'a decidedhazard into the manufacturing operations.

The object of my invention is a modified'black 5 I powder. compositionpossessing a high degree of thermal stability. A further object is sucha,powder containing ammonium nitrate as a portion of the oxidizingmateral, and having the composition so adjusted that the tendency tospontaneous l0 ignition on heating is removed. Further objects will bedescribed as the invention is disclosed hereinafter.

- I have found that the above objects are accomplished when the blackpowder composition contains a stabilizing ingredient consisting of asolid organic basic compound. While the inclusion of such an ingredientis particularly desirable in black powders containing ammonium nitrateas a portion of the oxidizing material, I may include this stabilizer toadvantage also in all types of black powders. Various compounds-may beused, with beneficial results, preferably from the class of solidaliphatic basic compounds, for example guanidine, dicyandiamide, urea,and the 5 like. Various aromatic basic compounds likewise may beemployed, such as diphenylamine. Preferably I make use of urea forbringing about the desired results.

As an illustrative example of a black blasting powder, made inaccordance with my invention, the following may be cited, in comparisonwith a similar powder containing no stabilizing ingredient of the typedescribed:

- Per cent Per cent Sodium nitrate 60.5 60.0 Sulfur 10.0 10.0 Charcoal18.0 17.8 Ammonium nitrate 10.0 10.0 40 Calcium carbonate 1.5 1.2 Urea1.0

The stabilizing value of the urea present in the second example abovemay be seen from the fact that the powder, containing no urea, firedspon- 5 taneously after 48 hours heating at 96 C., and after 7 to 8hours at 104 C. The powder containing the urea, on the other hand, firedonly after 19 hours at 116 C.- While urea or other stabilizingingredient of the class described may be used in a wide range ofamounts, I preferably include the urea in an amount between 0.2 .andOther, quantities may be used, but amounts below the lower limitgiven-are substantially insufiieient to bring about the'desired effecton the powder-composition, while more than 10% is undesirable because ofits effect on the explosiveproperties of the powder. It will beunderstood also that the various organic basic compounds suggestedherein will act as combustible in the explosive, as wellas in thecapacity of stabilizing agent.

The stabilizing ingredient according to my invention may be includedwith advantage in all forms of black blasting powder, whether granularorpelleted. Likewise it is applicable in low density powders of the typethat is obtained by packing the powder in wet condition into preparedand pre-formed shells, and s bsequent drying in the shell by means ofhea In fact, the desirability of powders containing a solid organicbasic compound as a stabilizer is emphasized particularly, the greaterthe amount of moisture present for removal, with consequent necessityfor maintaining at a relatively high temperature. for-a considerableperiod of time.

Having. described my invention in detail in the foregoing, I intend tobe limited only as indicated in the following claims.

I claim:

1. The process of stabilizing a modified black powder composition whichcomprises incorporat ing therein an ingredient comprising a solidorganic basic compound.

2. The process of stabilizing a modified black powder composition whichcomprises incorporating therein a solid aliphatic basic compound.

3. A modified black powder composition having its degree of stabilitysubstantially increased by an ingredient incorporated therein comprisinga solid organic basic compound.

4. A modified black powder composition containing ammonium nitrate as aportion of the oxidizing material, said composition having its degree ofstability substantially increased by an degree of stability increased byan ingredient incorporated therein comprising a solid aliphatic basiccompound.

'7. The composition of claim 4 in which the solid organic basic'compoundis diphenylamine.

8. The composition of claim 4 in which the solid organic compound isdicyandiamide.

9. The composition of claim 4 in which the solid organic basic compoundis urea.

10. A modified black powder composition comprising ammonium nitrate, asecond inorganic N nitrate, sulfur and charcoal, said composition havingits degree of stability increased by an ingredient incorporated thereincomprising a solid organic basic compound;

11. A modified black powder composition comprising sodium nitrate,ammonium nitrate, sulfur, charcoal, and sufficient urea to act as astabilizer. I 12. A modified black powder composition containingammonium nitrate as a portion of the oxidizing materia and a stabilizercomprising 0.2 to 10.0% of urea.

CLARENCE w. BROOKS, JR.

